Electrocatalytic activity of 4-nitrophthalonitrile-modified electrode for the l-glutathione detection

The present work describes the substantial electrocatalytic activity of (NC)2C6H3–NHOH/(NC)2C6H3–NO redox couple-modified electrode toward the low voltage detection of l-glutathione (GSH), in neutral medium, at an applied potential of 0.4 V versus Ag/AgCl. After optimizing the operational conditions, the sensor provided a linear response range for GSH from 8.0 up to 83.0 μmol L−1 with sensitivity, detection and quantification limits of 54 nA L μmol−1, 2.7 μmol L−1 and 8.0 μmol L−1, respectively. The proposed sensor presented higher sensitivity when compared to other modified electrodes described in the literature and showed a stable response for at least 100 successive determinations. The repeatability of the measurements with the same sensor and different sensors, evaluated in terms of relative standard deviation, were 4.1 and 5.0%, respectively, for n = 10. The developed sensor was applied for GSH determination in yeast extract and the results were statistically the same with those obtained by the comparative method described in the literature at a confidence level of 95%.